Italian champions Juve announced his arrival with a picture of the Argentine striker holding up Del Piero's old number 10 jersey alongside club president Andrea Agnelli.
A statement said he had reached a deal to sign a three-year-contract. There was no word on the transfer fee but media reports have put it at 12 million euros.
"The Argentine is used to winning. He has done so wherever he has been," Juve's website added.
Del Piero spent almost 20 years at Juve, helping them win the 1996 Champions League and sticking by the club when they spent one season in Serie B in 2006/07 after being demoted for match-fixing.
He left for Australia's Sydney FC last year having broken almost every Juve record in the book. Michel Platini and Roberto Baggio also famously wore Juve's number 10 shirt.
Handing Tevez the ex-Italy striker's former shirt is a mark of intent from Juve, who have won the Serie A twice in a row without a big name forward but are now targeting renewed European glory.
Coach Antonio Conte has rotated between any two of Sebastian Giovinco, Alessandro Matri, Mirko Vucinic and Fabio Quagliarella, who have shared the goals evenly between them.
Athletic Bilbao forward Fernando Llorente joins Juve next month.
Matri could now be sacrificed to suitors AC Milan, who had been tracking Tevez.
Earlier Tevez was whisked to Turin after hundreds of fans greeted him amid chaotic scenes at Milan's Malpensa airport.
Television pictures showed Tevez being mobbed by fans before being taken back into the terminal by Juventus staff and put into a car via a side entrance.
During his seven years in England the spotlight, whether positive or negative, was never far from the 29-year-old.
Tevez, along with fellow Argentine Javier Mascherano, arrived at Premier League side West Ham United in 2006 from Brazilian club Corinthians and had an immediate impact.
West Ham, struggling to remain in the top flight, were rescued from relegation by Tevez who scored the only goal in a win against Manchester United on the final day of the 2006/07 season.
CONTROVERSIAL MOVE
Despite the success of Tevez and Mascherano, their registrations were owned by third parties - a contravention of Premier League rules.
West Ham were fined for their role in the transfer deals, but Tevez had worked his magic and was promptly on his way to Manchester United.
At Old Trafford, Tevez helped the side to two league titles, the 2008 Champions League and 2008 FIFA Club World Cup.
But his relationship with manager Sir Alex Ferguson soured and he sealed a controversial move to United's arch-rivals Manchester City in July 2009.
Following his arrival, an infamous billboard stating 'Welcome to Manchester' with a picture of Tevez in a City shirt made his former employers at United boil.
Tevez's first two seasons at City were highly productive and h
